The present embodiments relate to apparatus and methods to reduce the temperature of liquids used in for example the food processing and preparation industries.
Rapid chilling of food products allows for greater production of same and greater flexibility to process high heat load input products of different types. In, for example, the meat processing industry, processors are usually limited to sixteen hour work days. Increased, more effective processing thereby eliminates weekend shifts, as the processor can now operate at full production during the week and/or reduce overtime.
Increased chill speed of the product reduces bacteria growth on the product; while product temperature, consistency, pull down rate and quality are all improved.
The food industry currently reduces the chill cycle time with known mechanical systems, including a freon/cold water/glycol jacketed vessel.
In order to chill liquid food products, such as pie fillings, pizza sauce, gravies and marinates, in the confection, bakery and meat industries, the food industry employs mechanical chilling systems and other methods such as a water-to-sauce heat exchanger to chill liquid products. In such methods, and using a liquid sauce for example, the sauce is drawn directly from a hot source (cooking/pasturization) and quickly cooled down through the 40° F. (4.4° C.) zone to control bacterial growth. The more quickly the liquid batch is cooled, the greater the output of product and/or the fewer cooling kettles/vats/vessels that are required during the cooling process.
Most known mechanical chilling systems include a compressor, a coil and an expansion valve, and a refrigerant such as freon or ammonia to chill glycol which transfers the temperature through a jacketed container. All mechanical chilling systems are limited by the size of these components and to the efficiency of the refrigeration cycle. It is also known to use water circulated through the jacket and/or a shell, and a tube heat exchanger for heat transfer.
Mechanical chilling methods are limited in their chilling capacity and require longer periods of time to dissipate the heat load in the product. Such limitations include the following factors:    limited to the size and design of the mechanical system/unit, ie higher initial heat loads, with summer temperatures requiring more time to cool;    limited to a warmer chill temperature difference, ie sized to chill loads at between −20° F. (−29° C.) and −40° F. (−40° C.) (limited to capacity of the chilling system and the refrigerant);    large hot loads overwhelm the system and create increased chill time. The mechanical unit is a closed loop system with a design that absorbs a limited heat input and largely relies on conductive heat transfer through coils. When the heat load is first introduced, the system struggles to remove the heat. Over time, the refrigeration system will become more effective, but this takes a long period of time;    moisture from hot loads evaporates and condenses, then settles and coats the heat exchange coils, thereby greatly reducing chill/freeze efficiency and increasing process time; and    use of a hot defrost to eliminate the frost build up on the coil which therefore introduces additional heat and adds time/electrical costs to the process.
Historically, most injectors and nozzles/lances were constructed with materials such as stainless steel. These materials provide excellent conductive heat transfer through the metal surface to the product. This is, however, operationally undesirable as it is prone to blockage as the liquid product rapidly freezes and builds on the contact surface until frozen product blocks or dams the pipe flow or freezes the liquid into a block onto the lance surface. As a result, the industrial gas industry and the food industry have yet to develop a working sauce chilling method or associated apparatus.
Known mechanical chilling systems are therefore susceptible to processing deficiencies, and additional maintenance and cleaning with respect to condensation. The known systems require a considerable amount of maintenance and repair, which translates into increased oversight and operational support to run the conventional mechanical chilling system used for reducing the temperature of liquids, such as for example sauces, during food product processing.